What caused

Ruka to become a girl?

In episode 8, they jokingly try to alter

Ruka's gender to make her a girl

with a D-Mail, but what they do is scientifically crude and unlikely to do anything.

Then, they send another D-Mail which

changes Akihabara drastically

and it is after this change that Okabe discovers that Ruka has changed.

I thought it was the latter D-Mail that caused Ruka to change because it was the D-Mail directly before the change was realized, when people started behaving as if Ruka was

a girl all along.

However, when this latter D-Mail, which had an effect on the city,

is cancelled out,

Ruka is still

a girl.

Was it the former or latter D-Mail that caused Ruka to change?

Relevant episodes:

Episode 8

D-Mail sent to change Ruka's gender. Likely a failure as it just told Ruka's mother to change her diet.

Episode 9

Faris's unknown D-Mail which changes Akihabara.

Episode 10

Okabe discovers Ruka's gender change, spurred by how people treat her as a girl.

Episode 17

Okabe reverts Akihabara to its prior state.

Episode 18

Okabe has to revert Ruka to a boy.

  • i think it was former episode but okabe didnt realize it
    – JAAD
    Commented Dec 28, 2016 at 21:19
  • also to support my theory the later email send wasn't send that long back to have impacted ruka to become a girl
    – JAAD
    Commented Dec 28, 2016 at 21:22

4 Answers 4


It was the D-Mail Ruka sent that changed Ruka to a girl.

When Okabe sees Ruka, he doesn't realize Ruka has in fact become a girl. He only realizes after Faris' D-Mail that Ruka has become a girl.

Also to support this, Faris' D-Mail wasn't sent that long back to have affected Ruka's gender, as Ruka was born well before Faris' D-Mail was sent.


First, I want to make sure that we're all on the same page about whether we're talking about sex or gender here.

Nowadays, we generally make the following distinctions:

  • Sex generally refers to your biological sex; in other words, your anatomical and genetic traits.
  • Gender is more difficult to define, but it generally refers to the socially constructed characteristics of males and females as they apply to you, such as norms, roles, and relationships of and between groups of women and men.

It should be noted that in informal speak, people frequently use the terms interchangeably.

Luka's gender is more ambiguous and subject to debate (just look at the comments on Luka's wikia page), but in this case, we just want to talk about Luka's biological sex, which is more clear-cut. Let's review what happened:

  1. Luka was physically male before the D-mail.
  2. Luka sent a D-mail back to his pregnant mom's pager.
  3. And as Okabe discovers later on, this caused Luka to become physically female.

However, a baby's sex is determined at the moment of conception. So, because Luka's mom was already pregnant when the D-mail arrived, Luka's sex was already decided. No amount of eating vegetables can change that.

One explanation could be that the cause was some other time travel divergence, at a point in time before Luka's conception. Even if the divergence were completely unrelated to Luka's family, it could still cause random variations in the environment that could cause Luka's conception to go very slightly differently.

However, Faris's D-Mail was sent to a point in time after Luka was already born, so I don't think this explanation is very likely.

Another possible explanation could be that the D-mail caused a random variation in the environment that caused Luka to develop differently in the womb. For example, it could be that in the new timeline, there was a random genetic mutation that caused Luka to develop an intersex condition. They're not that uncommon.

It is indeed possible for someone with XY chromosomes to be physically female.

For example, perhaps Luka experienced a mutation in the SRY gene:

Mutations in SRY give rise to XY females with gonadal dysgenesis who appear to be normal females at birth, but at puberty do not develop secondary sexual characteristics, do not menstruate, and have fibrous gonads without eggs.

Or, perhaps Luka experienced a mutation in the AR gene and developed complete androgen insensitivity syndrome:

Androgen insensitivity syndrome (AIS) is when a person who is genetically male (who has one X and one Y chromosome) is resistant to male hormones (called androgens). As a result, the person has some or all of the physical traits of a woman, but the genetic makeup of a man.

At puberty, female sex characteristics (such as breasts) develop. However, the person does not menstruate and become fertile.

The complete form of this syndrome can occur in as many as 1 in 20,000 live births, so I think it's certainly a possibility.

Anyway, these are just my speculations.


I'm sure it was the first D-Mail that changed Ruka's gender and not the second one. It was sent to his mom and it advised her to eat vegetables.

To support it, there is a very logical reason: the situation changed by the second D-Mail could not in any way affect his mom from eating more vegetables .

  • 1
    Yeah, except eating more vegetables has not been proven to actually have anything with changing his gender.
    – Jack Pan
    Commented Dec 29, 2016 at 18:43

Scientifically, this is not possible.

It's part of the anime logic in a science fiction story about time travel. They introduced the idea that the mother eating more vegetables or meat influenced the gender of the child. While in our world that is obviously wrong, it seems to be true in this fiction world.

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